Re: [Gimp-developer] Tuning and choosing resampling methods in GEGL/GIMP

[Øyvind Kolås <pippin gimp org>]

On Mon, Oct 23, 2017 at 3:51 PM, Elle Stone
<ellestone ninedegreesbelow com> wrote:
> Agreeing with what you say, I've tried lohalo and never saw any reason to
> use it instead of nohalo. For several years now nohalo is the only
> downsizing method that I use.
>
> I see in the git log that some changes have been made recently to nohalo. I
> haven't used the new version of nohalo, and also haven't added these changes
> to my "CCE" version of GIMP. The reason I mention this is because even
> though nohalo (the older version of nohalo) is slow, it produces results
> that are exceptionally good.
>
> The recent GEGL commit 0b0ecbb67198d6318ed163522e5233ecbc18ff25 mentions
> slightly sharper results for nohalo: "for sigificant downsampling this might
> result in sharper/aliased results".
>
> This "sharper/aliased results" doesn't sound like a good thing, at least not
> for my particular workflow. I don't use a lot of sharpening in my workflow,
> and I prefer to do any required post-downsizing sharpening by hand, using
> masks and layers, and using either unsharp mask or high pass sharpening, on
> an image by image basis.
>
> Would there be the possibility of parameters with the revised nohalo that
> would allow to replicate the old results?

This is what an adaptively increasing the OFFSET0 constant for
significant downscaling in the sources might achieve - do note that
what is meant by significant downscaling here is when scaling down to
below 1% of original size - even in such scenarios nohalo will already
be doing a good job. I believe that even without further enhancement
we should use nohalo as the default sampler.

/pippin